In order to enhance the serviceability of an electrophotographic print engine, some systems in the past have incorporated a "cartridge" concept wherein certain portions of the engine are enclosed in a removable cartridge. This allows all elements in the cartridge to be replaced at a single time.
One conventional example of the cartridge concept is that utilized with respect to toner cartridges. In toner cartridges, the toner, the toner delivering apparatus, the photoconductor drum and the cleaning blade or various elements are contained in a single module. This allows a user to both replenish the toner and to also replace all the components that would be subjected to wear over the duration of a given toner capacity of a cartridge. Typically, the elements that wear in the cartridge are of a lower quality than those used in non-cartridge based machines. Therefore, the cartridges can be manufactured with less expensive components, as compared to machines that only allow replacement of the toner. When the elements such as the photoconductor drum, the cleaning blades, etc. wear out in non-cartridge machines, it is necessary to place a service call, which can be relatively expensive compared to the price of the actual machine itself.
When servicing a print engine, it is usually necessary to perform a number of alignment tasks to ensure that the copier is obtaining adequate registration. This is especially the case with a copier utilized to generate multi-layer copies, such as in a color print engine. It is important in color print engines that the multiple copies have a very tight tolerance on registration to ensure that any overlapping of images for the various developing steps are minimized. However, when parts such as the photoconductor drum, etc. are replaced, this alignment can be an important and time consuming procedure for the service technician.
In one type of color copier system, that disclosed in U.S. Pat. No. 4,652,115, issued to the present Assignee, an intermediate transfer system is disclosed which requires very tight registration tolerances with respect to a photoconductor drum and an intermediate transfer member. Whenever any portion of the main photoconductor drum or the intermediate transfer member are replaced or adjusted, a service technician must assure that the alignment is correct. This renders the system a virtually nonuser-friendly system, wherein a user cannot perform any of the service himself and must rely upon a service technician.
In view of the above disadvantages, there exists a need for a system for decreasing the maintenance requirements for color copiers, especially for ones that require tight registration tolerance.